Ten Minutes Without a Guard
In a fabrication shop the last lot of a school order, 18 window-gate frames, must be dispatched tomorrow. At 4 p.m. the angle grinder's guard is found cracked and is removed. The supervisor says it is ten minutes of grinding, nothing will happen, so finish it. The only cutting disc left is marked maximum 6,600 rpm; the grinder nameplate reads 11,000 rpm. The trainee's goggles are scratched and fog up, so the supervisor tells him to work without them because they are only needed for cutting. The trainee is 17, on a stipend, and has been told that refusing work will be noted in his progress report. Two other workers are grinding nearby with no screens between the positions, and a pile of oily rags sits beside the welding bay.
1. Identify the hazards in this situation and explain, with reasoning, why the disc speed mismatch is the most serious one.
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- Unguarded wheel: the guard is the primary barrier against a burst disc and against hands or clothing entering the wheel. Removing it removes the only containment.
- Speed mismatch (most serious): the disc is marked 6,600 rpm maximum and the machine runs at 11,000 rpm, which is 1.67 times the rated speed. Centrifugal stress rises with the square of speed, so the disc would be loaded to about 2.8 times its design stress and can burst without warning, throwing fragments across the shop. The rim speed, not the sound of the machine, decides this; a disc must never run above its marked maximum. Either fit a disc rated 11,000 rpm or above, or use a slower machine.
- Eye injury: grinding without goggles, while two other workers grind nearby without screens, sends sparks and fragments metres across the bay.
- Fire: oily rags next to the welding bay will take a spark or a piece of slag; rags belong in a lidded metal bin.
- Organisational: a 17-year-old trainee directed to do unguarded work under threat, with no supervision of the other grinding positions.
2. Describe exactly how the trainee should respond on the shop floor so that the deadline is still met.
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In this order:
- Stop and make safe: switch off and unplug the grinder, put it out of use, and keep the cracked guard and the 6,600 rpm disc together as evidence.
- Tell the supervisor plainly and factually, without arguing about the deadline: this disc is rated 6,600 rpm and the machine runs at 11,000 rpm, so if it bursts it will go through someone; I am not running it; I need a correctly rated disc and a guard, or another method.
- Offer the alternative that saves the deadline: the 18 frames can be deburred on the pedestal grinder or with a file and hand scraper, and only the weld dressing waits for the right disc, which stores can issue or the local dealer can supply the same evening. Splitting the job protects the dispatch date.
- Get proper eye protection: scratched goggles must be replaced from the store, not skipped; ask for screens between the grinding positions and move the oily rags to a lidded metal bin.
- Escalate the same day to the safety officer, instructor or principal if the instruction is repeated. Reporting an unsafe instruction is not insubordination; it is the required action.
3. What should be recorded or reported afterwards, and how would you judge the supervisor's conduct and the threat about the progress report?
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Record: an entry in the workshop register or near-miss form giving date, time, machine number, disc marking, guard condition, the instruction received and the action taken; a note that the grinder is out of service until a guard and a correctly rated disc are fitted; a check of the discs on the other grinders; and the disposal of the oily rags in a covered metal container. Keep a copy - a verbal report disappears when the shift changes.
Judging the supervisor's conduct: an instruction to work unsafely does not become lawful because a supervisor gave it. The employer has a duty under the Factories Act 1948 to guard machinery and to provide protection for the eyes, and the trainee has a duty to himself and to the two workers grinding next to him not to create a burst-disc hazard. A guard that is cracked is a maintenance failure, and the correct response is to raise a maintenance request, not to remove the guard.
The threat: using a progress report to force compliance is retaliation and should be reported in writing with the near-miss record. The trainee's obligation is to be firm, factual and to use the escalation route - not to keep quiet and hope the disc holds.